WASHINGTON, Jan 9 (Reuters) - Federal prosecutors face a difficult task if they try to prosecute members of New Jersey Governor Chris Christie's staff and state officials in connection with a massive traffic snarl on a busy commuter bridge that has triggered a political storm.

Emails released on Wednesday appeared to show Christie's aides and an executive of the Port Authority of New York and New Jersey, which is responsible for the region's ports and bridges, planned the lane closings last September. Christie's political opponents have said the closures were part of a vendetta against the Democratic mayor of Fort Lee, at the New Jersey end of the George Washington Bridge, because he had declined to endorse the Republican governor's re-election effort.

A spokeswoman for the U.S. Attorney in New Jersey said on Thursday that office was reviewing the allegations, which are already the subject of a state legislature inquiry and a Port Authority inspector general review.

But a lack of relevant federal statutes, and a 2010 Supreme Court ruling that narrowed a public corruption law, could prevent federal authorities from advancing the preliminary review into a criminal case.

"They are probably combing through the statute book looking for statutes that haven't been used in a long time because one does not jump out at you," said Andrew Lourie, a former chief of the Justice Department's public integrity section and now a defense lawyer at Kobre & Kim LLP.

There has been no suggestion so far that any money changed hands, and most federal corruption laws require prosecutors to prove that money was involved or some explicit quid-pro-quo took place.

Christie, a possible 2016 presidential candidate, said on Thursday he had no knowledge that his staff was involved in the four-day lane closings on the bridge and fired a top aide at the center of the scandal.

Responsible officials could face private lawsuits from individuals harmed by the delays, or they could face charges under state law.

A federal investigation could have been more conceivable before the Supreme Court's 2010 ruling in the case of former Enron executive Jeffrey Skilling, experts said.

In that case, the high court pared back a law that says public officials or others can be prosecuted for failing to provide the public with its "intangible right to honest services." Instead, the court said prosecutors had to prove bribes or kickbacks were at issue.

One open question is whether any of the fired officials will provide investigators with incriminating information or turn on their former superiors.

One of those officials, former Port Authority executive David Wildstein, appeared on Thursday before a state legislative panel investigating the matter. But he declined to answer questions, repeatedly invoking the constitutional protection not to say anything that might incriminate him.

Another issue is whether any evidence surfaces that shows state officials obstructed federal agents looking into the matter or lied to them.

"If the feds are investigating, there is always the danger to anyone being investigated, that if they are not 100 percent truthful, or they delete or destroy or hide evidence, then they could be guilty of obstruction of justice," said Peter Zeidenberg, a former federal prosecutor who helped prosecute former Bush administration official Lewis "Scooter" Libby on similar grounds.

Libby, who served as Vice President Dick Cheney's chief of staff, was convicted in 2007 of obstructing a CIA leak probe.

But Zeidenberg said barring new evidence, he did not anticipate a criminal case from federal prosecutors.

"It's political payback and it's mischief, but crime? I can't think of one," said Zeidenberg, now a lawyer with DLA Piper. "There are some creative people over there - maybe they'll come up with something." (Reporting by Aruna Viswanatha; additional reporting by David Ingram and Edward Krudy; Editing by Karey Van Hall and Dan Grebler)